Concrete and asphaltic surfaces such as airport runways and automobile highways, and particularly concrete airport runways, often collect a mixed residue of rubber particles marking paints, oil drippings, dirt, and other undesirable contaminants.
Airport runways are particularly susceptible to this phenomenon because of the violence with which rubber tired aircraft landing gear make contact with runway surfaces, which contact results in heavy deposits of rubber from the tires of the aircraft. In addition, runways carry extensive painted markings thereon to guide pilots in landing and taxiing in and to the proper areas. These painted markings eventually weather, crack, and peel to the extent that they may become difficult or impossible to read clearly, plus they further add to the deposits of contaminants. Other contaminants include the droppings of oil and spilled fuel on the runways both from the aircraft and from ground vehicles used in refueling and maintenance of the aircraft.
The results of these factors are twofold. First, the peeling of painted markings, plus the deposition of rubber and other substances over the non-peeled remainder of the markings results in obliterating the vital runway markings which creates a very dangerous situation with respect to aircraft landing and taking off.
A second undesirable effect of the substances deposited on the runways is the resultant loss of traction between the landing gear and the surface of the runway. This is a particularly hazardous situation when huge jet aircraft are landing at night on a rain or snow wetted runway. The mixture of natural precipitation on a rubbery, oily surface serves as a very efficient lubricant between the landing wheels and the runway and prevents, in many cases, the stopping of the aircraft within a safe distance. Add to this the effect that because of the night, the partially obliterated markings, and the weather, the pilot may not be able to set the aircraft down in a position to utilize the maximum length of the runway. In that situation braking ability is critical.
One solution to the painted marking obliteration problem is to entirely remove the obliterated markings from the runway surface and repaint the markings afresh. One solution to the loss of traction is similar; the contaminants must be removed.
In the past this has involved a messy and time consuming process of spraying chemical solvents on the runways in order to dissolve the rubber, oils, fuels, and paints thereon, allowing the solvent to work for a sufficient time, and then flushing the surface with a washing solution.
This process is basically undesirable for two reasons. The first is the time element involved. For instance, Chicago's O'Hare field could not afford to close down a busy runway for the one or more days required to perform the above chemical process because it would place an unbearable overload on the remaining runways, causing extremely hazardous air traffic congestion.
The second problem is that of ecological pollution. The dissolved contaminants, the solvents, and the washing solution which run off the runway eventually find their way into streams, lakes, and municipal water supplies. These solvents and the reaction products therefrom are noxious and even poisonous and therefore it is mandatory that they be prevented from entering any body of water.
One method that has been used in the past to clean these surfaces without the use of solvent has been to utilize hand-carried lances to apply streams of high pressure water to the contaminants to jet-blast them from the surface. While this has partially solved the ecological problem, it has only worsened the time factor since the hand-lancing technique is even more time consuming than the solvent method.
The present invention overcomes these problems by providing apparatus which can quickly and efficiently apply a broad pattern of high pressure water or neutral-fluid spray to the surface to be cleaned in a fast moving, broad sweeping cleaning action, which apparatus can almost instantly be temporarily removed from the surface being cleaned in case an emergency need for the runway or roadway arises. The apparatus also provides extremely swift yet effective means of removing deposits from the desired surfaces without harming these surfaces.